The volume of qualitative studies forced a quantitative-only restriction.

Evidence

Given the quantity of screened-in scientific articles, we decided to confine the literature review to quantitative studies only, adding an eighth and final inclusion criterion: 8. — Lea Echelmeyer, Anne-Marie Slotboom, and Frank Weerman, The Putative Effect of Identity on…, 38

Categorization

• XREF: Directly explains why the reader’s stated task — reviewing quantitative studies — is itself a design restriction rather than a neutral scope.